That's how you're supposed to feel. I thought I knew what was going on like 4 times playing that game.

You can if you record yourself with a video camera and then move the video over to your PSP with some PC wizardry.

DX10 seems to affect the particles the most. Looking that the screens it looked like the mist/smoke in dx9 was sort of thicker "cough cough, I have asthma", and on dx10 it looked a little more whipsy. Kind of an, "excuse me, what's all this mist doing here". Totally...

A geforce 6150 will run games like Doom 3 and Half-life 2 pretty well. I play Doom 3 on a 5200, which is by no means a recommendation. You'll probably get some low or medium quality Quake 4 action out of it too. So... games that came out 1 or 2 years ago and anything before that.